A few weeks ago I upgraded to 640MB RAM, and sudently I could do anything on the PC,
but lately, whenever I play music, either in MediaPlayer or Winamp, the computer gets very slow, and when I check the CPU usage on the "windows task manager", it says 100% CPU usage, and some times it even gets stuck...
Is there any setting I could modify, anything?

The driver thing seems to have worked!,
I just de- and re-installed the drivers and now it seems to be fine, I'll keep testing.

and "enoughfakefiles": Im using winamp, but about the visuals on Media Player,
you're right, they take a heavy toll on speed and memory,
and they aren't even atractive, exept the new one with the bars.

crap, still the same problem.
So far, I've only manage to isolate somethin: that when I use "Real Player" (that I dld for a moment necesity), the CPU Usage is almos non existing, meaning very low, so I can work without truble on my PC, but as soon as I use WinAmp, it starts again.
I also went to the Control Panel's 'Sound and Audio Devices', 'Audio Tab', 'Advance button on Sound Playback', then 'Performance tab', and once there, I reduced the "Hardware Acceleration", but as soon as I start playing something, it goes to maximum again.
By the way, on "Default Device", it says 'Realtek AC97 Audio'.

The one thing Im planing on trying next is, re-instal Windos Media Player, may be it will re-set something... but thats just me.

Any sugestions so far?, anything?
*except trowing my PC to the garbage or something of the sort. .

uhmmmmm...........
if winamp is sucking all the CPU, why reinstall WMP?
sounds like a software issue to me, like, winamp sux
that would be like all the ppl who've had trouble with soulseek reinstalling BT to fix it